The present invention relates to a process for the construction of a composite tube, comprising a metal tube, in particular a tube of copper, and a cladding of tubular form into which the tube itself is inserted. The said cladding material is deformable foam material, in particular foam rubber. The composite tube obtained with the process of the invention is particularly suitable for use in plumbing systems requiring a thermal insulation sufficient to impede the dispersion of thermal energy to the environment in which the composite tube is disposed.
As is known, in plumbing installations there is very often required a thermal insulation of the tubes through which hot fluids traverse, for the purpose of preventing the dispersion of energy into the external environment.
At present, in order to obtain such insulation, pieces of cladding material of tubular form are normally used. The pieces are cut substantially along a generatrix, subsequently opened and fitted around the metal tube to be insulated, so that they adhere tightly thereto.
The said pieces are provided by cutting from cladding of tubular form and greater length. The claddings are normally made from a synthetic foam material, usually foam rubber, and therefore have a significant quantity of closed cells, or cells in communication with one another, so as to provide a good thermal insulation. The said tubular cladding is normally obtained by means of a process which comprises an extrusion phase and subsequent thermal treatments during which the cladding itself is subjected to numerous operations which must necessarily be performed after the extrusion operation itself, and which operations require rather a long time.
Composite tubes are also known, for example copper tubes which have an outer cladding of a thermo-plastic material, normally polyvynyl chloride, which is extruded directly onto the tube. Although these tubes are provided with an outer cladding they do not, however, have a sufficiently high thermal insulation to prevent transmission of thermal energy towards the external environment, and therefore they are not suitable for the majority of applications in plumbing installations.